Battery voltage 14.5

[adallak]

I used to check the voltage while driving and as far as I remember it was around 13.7 V. Recently I noticed the voltage is between 14.1 and 14.5 all the time regardless how long I have been driving. Does it mean the generator is on all the time? Is not the regulator supposed to turn it off when battery is charged completely? s the battery bad?

The latter is five years old and I never had hard time starting the car unless it is hot.

[Ranger]

I'll let someone who knows electronics more that I answer but I can tell you that mine runs in the low 14's except when I have the A/C on, then it's in the high 13's.

[acklac7]

While were on the subject, mine runs in the high 12's to low 13's...Never goes above 14...Is this normal?

[MAC]

My alternator will produce 14.1 + volts. I’ve seen it at 14.5 many times. However, it does not remain there all of the time. It may remain at 14.0 – 14.2 for quite some time, but it will usually drop to the 13.8 –14.0 range. If your alternator is producing abnormally high volts it could be a sign that the battery is not charging fully. Perhaps there’s a bad ground or the positive side is corroded such that the alternator is trying to pump enough volts into the battery to fully charge it. I remember this was a suggestion made by a member in a post several months ago on the same topic.

[Logan]

I wouldnt worry...

My 2001 Deville will display 16.1 v at times.....

I think I contacted JimD about this once.... His does the same...

[JimD]

I used to check the voltage while driving and as far as I remember it was around 13.7 V. Recently I noticed the voltage is between 14.1 and 14.5 all the time regardless how long I have been driving. Does it mean the generator is on all the time? Is not the regulator supposed to turn it off when battery is charged completely? s the battery bad?

The latter is five years old and I never had hard time starting the car unless it is hot.

Ninety percent of the reason for the battery in your vehicle is to provide energy for the starter motor. If your battery will power the starter motor and crank the engine each and every time you turn the key, your battery and generator are operating as designed.

With the engine running, the generator supplies all the electrical energy all the time including sufficient energy to recharge the battery from the last time the engine was started. Under extreme high load situations (such as engine at idle, headlights and fog lights on, HVAC fans on high speed, and radio cranking out high volume tunes), the generator voltage could drop to a point where the battery will start contributing energy to the system.

The voltage readings can provide a clue about the general health of the electrical system. And the system voltage will vary slightly with temperature. Cruising down the highway, you can expect to see system voltage somewhere between 13 and 16 volts.

The acid test (pun intended) for your battery and charging system is the starter motor test in my first paragraph.

This system voltage deal is similar to the questions about coolant temperatures ranging between 200 and 230 degrees F. Nothing wrong with a little variation so long as your system remains within a given range.

[adallak]

Thanks you for the replies gentlemen! I think the charging system's components are still within specs but the voltage definitely changed from 13.7 to 14.* what most likely indicates some degradation of battery, cables and connections.

[johnnydone]

my 2cents worth goes back to experiences with my allante

today we use sealed batteries but believe it or not eventually they need water

since we cant put water in them they start losing their ability to hold a full charge]

in todays market the only solution is to put a fresh battery in and of course clean the heck out of your cables

[KHE]

Thanks you for the replies gentlemen! I think the charging system's components are still within specs but the voltage definitely changed from 13.7 to 14.* what most likely indicates some degradation of battery, cables and connections.

I wouldn't worry about 0.3 volts difference at all.

[Scotty]

I see seasonal differences but typically its higher in the cold weather. If you perceive a jump in 'normal' volts it may make sense to have your battery checked you might be seeing the result of a dead or dying cell, Mike

[Oldgamer]

adallak:

JimD gave you correct info, I just want to add something, and so you will see the whole picture. The regulator doesn't care about your battery. It just trying to keep the voltage produced by alternator on the same level, not higher than some value, let say 13.7 volts. It constantly compares that value to the system voltage. If system voltage is lower regulator connects the wire of the rotating coil to the current source. When system voltage became higher than base value, the regulator disconnects that wire from the power source and alternator' voltage drops (pretty quick actually). That's why in reality the current of this wire under constant modulation. How I recall, the system voltage should not be higher than 16 volt or something like that. Constant overcharging is bad to the battery and leads to short battery life. If you noticed that voltage became higher than usual a little bit it doesn't mean that something is wrong. It's nothing to do with battery connections. Possible, the battery gets older a bit and it's higher than usual internal resistance is lowering charge current. Don't worry about it now if it still starts engine fine.

[Scotty]

I just found this:

A car's charging system is composed of an alternator (or DC generator), a voltage regulator, battery and indicator light or gauge. While the engine is running, it's purpose is to provide power for the car's electrical load, e.g., ignition, lighting, accessories, etc., and to recharge the car's battery.

When the charging system fails, usually an indicator light will come on or the gauge will not register "good". The most common charging system failure is a loose, worn or broken alternator belt, so check it first. If OK, then with a known good battery and the engine running at 2000 RPM or more for two minutes, depending on the load and ambient temperature, the voltage should increase to between 13.0 and 15.1 volts. Most cars will measure between 14.0 and 14.5 volts on a warm day. [Most voltage regulators are temperature compensated to properly charge the battery under different environmental conditions. As the ambient temperature decreases, the charging voltage is increased to overcome the higher battery resistance (cold weather). Conversely, as the ambient temperature increases, the charging voltage is reduced. Other factors affecting the charging voltage are the battery's condition, state-of-charge, electrical load and electrolyte level and purity.]

If terminal voltage is below 13.0 volts and the battery tests good after being externally recharged or if you are still having problems keeping it charged, then have the charging system's output voltage and current and car's parasitic (key off) load tested. A loose alternator belt or bad diode will significantly reduce the alternator's current output.

If output voltage is above 15.1 volts with the ambient temperature above freezing, the battery's electrolyte level is frequently low, or you smell "rotten eggs" around the battery, then you are probably overcharging the battery and the charging system should be tested.

[Oldgamer]

I just found this:

A car's charging system is composed of an alternator (or DC generator), a voltage regulator, battery and indicator light or gauge. While the engine is running, it's purpose is to provide power for the car's electrical load, e.g., ignition, lighting, accessories, etc., and to recharge the car's battery.

When the charging system fails, usually an indicator light will come on or the gauge will not register "good". The most common charging system failure is a loose, worn or broken alternator belt, so check it first. If OK, then with a known good battery and the engine running at 2000 RPM or more for two minutes, depending on the load and ambient temperature, the voltage should increase to between 13.0 and 15.1 volts. Most cars will measure between 14.0 and 14.5 volts on a warm day. [Most voltage regulators are temperature compensated to properly charge the battery under different environmental conditions. As the ambient temperature decreases, the charging voltage is increased to overcome the higher battery resistance (cold weather). Conversely, as the ambient temperature increases, the charging voltage is reduced. Other factors affecting the charging voltage are the battery's condition, state-of-charge, electrical load and electrolyte level and purity.]

If terminal voltage is below 13.0 volts and the battery tests good after being externally recharged or if you are still having problems keeping it charged, then have the charging system's output voltage and current and car's parasitic (key off) load tested. A loose alternator belt or bad diode will significantly reduce the alternator's current output.

If output voltage is above 15.1 volts with the ambient temperature above freezing, the battery's electrolyte level is frequently low, or you smell "rotten eggs" around the battery, then you are probably overcharging the battery and the charging system should be tested.

Scotty: The adallak noticed higher voltage than usual, not lower, so it's nothing to do with loose belt or bad diode.